Fleet protection attack craft

ABSTRACT

A marine vessel comprising:
         a command module;   first and second buoyant tubular foils; and   first and second struts for connecting the first and second buoyant tubular foils to the command module, respectively;   wherein the first and second buoyant tubular foils provide substantially all of the buoyancy required for the marine vessel; and   wherein the marine vessel further comprises first and second engines enclosed within the first and second buoyant tubular foils, respectively, and first and second propulsion units connected to the first and second engines, respectively, for moving the marine vessel through the water.

REFERENCE TO PENDING PRIOR PATENT APPLICATIONS

This patent application is a continuation of pending prior U.S. patentapplication Ser. No. 12/485,848, filed Jun. 16, 2009 by Gregory E.Sancoff et al. for FLEET PROTECTION ATTACK CRAFT, which in turn claimsbenefit of:

(i) prior U.S. Provisional Patent Application Ser. No. 61/132,184, filedJun. 16, 2008 by Gregory E. Sancoff for FORCE PROTECTION ATTACK CRAFT;and

(ii) prior U.S. Provisional Patent Application Ser. No. 61/200,284,filed Nov. 26, 2008 by Gregory E. Sancoff et al. for FLEET PROTECTIONATTACK CRAFT (F-PAC).

The above-identified patent applications are hereby incorporated hereinby reference.

FIELD OF THE INVENTION

This invention relates to marine vessels in general, and moreparticularly to high-speed attack and reconnaissance craft.

BACKGROUND OF THE INVENTION

The terrorist attack on the guided missile destroyer USS Cole in Adenharbor in 2000 provided a devastating example of what a small group ofterrorists can do to a modern warship with minimal resources—in the caseof the USS Cole, two terrorists in a small boat carrying a few hundredpounds of explosives came close to sinking a billion dollar warship.

The success of the attack on the Cole has given rise to another, evenmore disturbing concern—that a large number of high speed boats, eachpacked with explosives and manned by suicide bombers, could create a“small boat swarm” which could overwhelm the defenses of a warship,particularly in restricted waters where reaction time andmaneuverability may be limited. Indeed, recent wargame simulationssuggest that such swarm tactics could prove extremely effective againstnaval battle groups operating in the narrow waters of the Persian Gulf.

It is currently believed that such “small boat swarm” tactics are bestcountered with fast, similarly-sized, highly-maneuverable andheavily-armed attack craft which can establish a defensive perimeter ata safe distance from the naval battle group. To this end,appropriately-outfitted Zodiac-type craft have already been deployed forthis purpose. However, experience has shown that these Zodiac-type craftare only practical in the relatively calm waters of a harbor. This isbecause operating these Zodiac-type craft at high speed in the turbulentwaters of the open sea imposes excessive physical stresses on the crewsthat can only be withstood for short periods of time. Furthermore, thedefensive perimeter should, ideally, be established at a substantialdistance from the battle group (e.g., at least 10 miles out), in orderto give the battle group sufficient time to react in the event that anyof the small boat swarm should penetrate the defensive perimeterestablished by the Zodiac-type craft. However, due to their lightconstruction, limited operating time at high speeds, and limitedfuel-carrying capacity, Zodiac-type craft are not capable of maintaininga reliable defensive perimeter so far out from the battle group. Inpractice, with Zodiac-type craft, the defensive perimeter must generallybe maintained much closer to the battle group, with the consequent lossof reaction time.

It has been suggested that attack helicopters might be used to protect anaval battle group when it is at sea or at anchor. However, these attackhelicopters generally have relatively limited range and, perhaps moreimportantly, relatively limited sortie time, which effectively preventsthem from maintaining a reliable defensive perimeter a substantialdistance out from the battle group. Furthermore, these attackhelicopters generally have substantial radar, infrared and visual“signatures”, thereby making them relatively easy to detect and target.

Thus, there is a need for a new and improved fleet protection attackcraft which can be used to maintain a defensive perimeter a safedistance out from a naval battle group. In this respect it should beappreciated that such a craft should be small, fast, highly-maneuverableand heavily-armed. Furthermore, the craft should provide a stableplatform even when running at high speed in substantial ocean swells,whereby to minimize physical stress on the crew and to provide a stableweapons platform. And the craft should be capable of remaining onstation for a substantial period of time, in order to maintain areliable defensive perimeter at a safe distance from the battle group.

There is also a need for a new and improved craft which can be used forreconnaissance, and/or to deliver small teams of special forces behindenemy lines and/or to extract the same. Thus, the craft should also becapable of “stealth mode” operation, i.e., it should have small radar,infrared, visual and noise signatures, thereby making it difficult todetect and target.

SUMMARY OF THE INVENTION

These and other objects of the present invention are addressed by theprovision and use of a novel fleet protection attack craft. The novelattack craft is small, fast, highly-maneuverable and heavily-armed. Thenovel attack craft provides a stable platform even when running at highspeed in substantial ocean swells, whereby to minimize physical stresson the crew and to provide a stable weapons platform. And the novelattack craft is capable of remaining on station for a substantial periodof time, in order to maintain a reliable defensive perimeter at a safedistance from a naval battle group. Thus, the novel attack craftprovides an effective means for defending against a “small boat swarm”,by establishing a defensive perimeter at a safe distance from the battlegroup and thereby permitting the interception, identification, warningand, if ultimately necessary, destruction of hostile boats long beforethey can approach the battle group.

In addition, the novel attack craft is also capable of “stealth mode”operation, i.e., it has small radar, infrared, visual and noisesignatures, thereby making it difficult to detect and target. Thus, thenovel attack craft also provides an effective means for conductingreconnaissance and/or for delivering small teams of special forcesbehind enemy lines and/or for extracting the same.

In one form of the present invention, there is provided a marine vesselcomprising:

a command module;

first and second buoyant tubular foils; and

first and second struts for connecting the first and second buoyanttubular foils to the command module, respectively;

wherein the first and second buoyant tubular foils provide substantiallyall of the buoyancy required for the marine vessel;

wherein the first and second struts are pivotally connected to thecommand module and fixedly connected to the first and second buoyanttubular foils, respectively; and

wherein the first and second struts comprise substantially rigid planarstructures.

In another form of the present invention, there is provided a marinevessel comprising:

a command module;

first and second buoyant tubular foils; and

first and second struts for connecting the first and second buoyanttubular foils to the command module, respectively;

wherein the first and second buoyant tubular foils provide substantiallyall of the buoyancy required for the marine vessel; and

wherein the marine vessel further comprises first and second enginesenclosed within the first and second buoyant tubular foils,respectively, and first and second propulsion units connected to thefirst and second engines, respectively, for moving the marine vesselthrough the water.

In another form of the present invention, there is provided a marinevessel comprising:

a command module;

first and second buoyant tubular foils; and

first and second struts for connecting the first and second buoyanttubular foils to the command module, respectively;

wherein the first and second buoyant tubular foils provide substantiallyall of the buoyancy required for the marine vessel; and

wherein the marine vessel further comprises first and second propellermechanisms mounted on the leading ends of the first and second buoyanttubular foils, respectively, for moving the marine vessel through thewater.

In another form of the present invention, there is provided a marinevessel comprising:

a command module;

first and second buoyant tubular foils; and

first and second struts for connecting the first and second buoyanttubular foils to the command module, respectively;

wherein the first and second buoyant tubular foils provide substantiallyall of the buoyancy required for the marine vessel; and

wherein the marine vessel further comprises a plurality of spoilersmounted on the first and second buoyant tubular foils for steering themarine vessel as it moves through the water.

In another form of the present invention, there is provided a marinevessel comprising:

a buoyant tubular foil; and

a propeller mechanism mounted on the leading end of the buoyant tubularfoil for moving the marine vessel through the water.

In another form of the present invention, there is provided a marinevessel comprising:

a buoyant tubular foil; and

a plurality of spoilers mounted on the buoyant tubular foil for steeringthe marine vessel as it moves through the water.

In another form of the present invention, there is provided a marinevessel comprising:

a buoyant tubular foil;

a propeller mechanism mounted on the leading end of the buoyant tubularfoil for moving the marine vessel through the water; and

a plurality of spoilers mounted on the buoyant tubular foil for steeringthe marine vessel through the water;

wherein each of the spoilers comprises a plate movable between (i) aninboard position wherein the plate is substantially aligned with theskin of the buoyant tubular foil to which the spoiler is mounted, and(ii) an outboard position wherein the plate projects into, and deflects,the water flowing by the buoyant tubular foil to which the spoiler ismounted.

In another form of the present invention, there is provided a method formoving through water, the method comprising:

providing a marine vessel comprising:

-   -   a command module;    -   first and second buoyant tubular foils; and    -   first and second struts for connecting the first and second        buoyant tubular foils to the command module, respectively;    -   wherein the first and second buoyant tubular foils provide        substantially all of the buoyancy required for the marine        vessel;    -   wherein the first and second struts are pivotally connected to        the command module and fixedly connected to the first and second        buoyant tubular foils, respectively; and    -   wherein the first and second struts comprise substantially rigid        planar structures; and

moving the marine vessel through water and adjusting the position of thefirst and second struts relative to the command module.

In another form of the present invention, there is provided a method formoving through water, the method comprising:

providing a marine vessel comprising:

-   -   a command module;    -   first and second buoyant tubular foils; and    -   first and second struts for connecting the first and second        buoyant tubular foils to the command module, respectively;    -   wherein the first and second buoyant tubular foils provide        substantially all of the buoyancy required for the marine        vessel; and    -   wherein the marine vessel further comprises first and second        engines enclosed within the first and second buoyant tubular        foils, respectively, and first and second propulsion units        connected to the first and second engines, respectively, for        moving the marine vessel through the water; and

moving the marine vessel through water.

In another form of the present invention, there is provided a method formoving through water, the method comprising:

providing a marine vessel comprising:

-   -   a command module;    -   first and second buoyant tubular foils; and    -   first and second struts for connecting the first and second        buoyant tubular foils to the command module, respectively;    -   wherein the first and second buoyant tubular foils provide        substantially all of the buoyancy required for the marine        vessel; and    -   wherein the marine vessel further comprises first and second        propeller mechanisms mounted on the leading ends of the first        and second buoyant tubular foils, respectively, for moving the        marine vessel through the water; and

moving the marine vessel through water.

In another form of the present invention, there is provided a method formoving through water, the method comprising:

providing a marine vessel comprising:

-   -   a command module;    -   first and second buoyant tubular foils; and    -   first and second struts for connecting the first and second        buoyant tubular foils to the command module, respectively;    -   wherein the first and second buoyant tubular foils provide        substantially all of the buoyancy required for the marine        vessel; and    -   wherein the marine vessel further comprises a plurality of        spoilers mounted on the first and second buoyant tubular foils        for steering the marine vessel as it moves through the water;        and

moving the marine vessel through water and adjusting the position of thespoilers.

In another form of the present invention, there is provided a method formoving through water, the method comprising:

providing a marine vessel comprising:

-   -   a buoyant tubular foil; and    -   a propeller mechanism mounted on the leading end of the buoyant        tubular foil for moving the marine vessel through the water; and

moving the marine vessel through water.

In another form of the present invention, there is provided a method formoving through water, the method comprising:

providing a marine vessel comprising:

-   -   a buoyant tubular foil; and    -   a plurality of spoilers mounted on the buoyant tubular foil for        steering the marine vessel as it moves through the water; and

moving the marine vessel through water and adjusting the position of thespoilers.

In another form of the present invention, there is provided a method formoving through water, the method comprising:

providing a marine vessel comprising:

-   -   a buoyant tubular foil;    -   a propeller mechanism mounted on the leading end of the buoyant        tubular foil for moving the marine vessel through the water; and    -   a plurality of spoilers mounted on the buoyant tubular foil for        steering the marine vessel through the water;    -   wherein each of the spoilers comprises a plate movable        between (i) an inboard position wherein the plate is        substantially aligned with the skin of the buoyant tubular foil        to which the spoiler is mounted, and (ii) an outboard position        wherein the plate projects into, and deflects, the water flowing        by the buoyant tubular foil to which the spoiler is mounted; and

moving the marine vessel through water and adjusting the position of thespoilers.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will bemore fully disclosed or rendered obvious by the following detaileddescription of the preferred embodiments of the invention, which is tobe considered together with the accompanying drawings wherein likenumbers refer to like parts and further wherein:

FIG. 1 is a schematic view showing a novel fleet protection attack craftformed in accordance with the present invention;

FIGS. 2-9 are schematic views showing further construction details ofthe novel attack craft shown in FIG. 1, including further details of itscommand module, buoyant tubular foils (BTFs) and struts;

FIGS. 10-15 are schematic views showing further details of the BTFs andstruts, and the internal components thereof;

FIGS. 15A and 15B are schematic views showing how a gaseous envelope maybe provided around the BTFs so as to reduce drag as the vessel movesthrough the water;

FIGS. 16-26 are schematic views showing further details of the spoilersused to steer the novel attack craft and adjust its attitude; and

FIGS. 27-36 are schematic views showing how the position of the strutsand BTFs can be adjusted relative to the command module.

DETAILED DESCRIPTION OF THE INVENTION Overview

Looking first at FIGS. 1-6, there is shown a novel fleet protectionattack craft 5. Attack craft 5 generally comprises a command module 100for carrying the crew, weapons and payload (including passengers), apair of buoyant tubular foils (BTFs) 200 for providing buoyancy,propulsion and steering, and a pair of struts 300 for supporting commandmodule 100 on BTFs 200.

As seen in FIGS. 4, 7 and 8, and as will hereinafter be discussed infurther detail, struts 300 can be disposed in a variety of differentpositions vis-à-vis command module 100, so that attack craft 5 canassume a number of different configurations, depending on the desiredmode of operation, whereby to provide high speed, extreme stability andstealth capability.

Thus, for example, in standard seas, attack craft 5 might be placed inthe configuration shown in FIG. 4 (i.e., so that struts 300 are disposedapproximately 45 degrees off the horizon, and at approximately a rightangle to one another) so that command module 100 is safely out of thewater and the vessel has modest radar, infrared and visual signatures.

However, in high seas, while operating at high speed, attack craft 5might be placed in the configuration shown in FIG. 7 (i.e., so thatstruts 300 are disposed substantially perpendicular to the horizon, andsubstantially parallel to one another) so that command module 100 standswell out of the water and is free from the affect of swells.

Furthermore, depending on sea conditions, attack craft 5 could be in aconfiguration somewhere between those shown in FIGS. 4 and 7.

Attack craft 5 is also designed to operate in stealth mode, by loweringits physical profile. In this case, attack craft 5 might be placed inthe configuration shown in FIG. 8 (i.e., so that struts 300 are disposedalmost parallel to the horizon, and almost co-linear with one another)so that command module 100 sits just above, or actually in, the water,reducing its radar, infrared and visual signatures. This mode can bevery useful when attack craft 5 is being used for reconnaissancepurposes and/or to deliver small teams of special forces behind enemylines and/or to extract the same.

Thus, in one preferred form of the invention, attack craft 5 is normallyoperated in the configuration shown in FIG. 4, with command module 100completely out of the water, but the command module being as low aspossible so as to have a reduced profile. However, in high seas and athigh speed, attack craft 5 may be operated on the configuration shown inFIG. 7, so that command module 100 stands well clear of any swells. And,when desired, attack craft 5 can be operated in the configuration shownin FIG. 8 so as to assume a stealth mode.

Or, attack craft 5 could be operated in a configuration somewherebetween those shown in FIGS. 4, 7 and 8.

Prior Art Designs for Achieving High Speed and/or Extreme Stability

There are currently two competing approaches for achieving high speedand/or high stability in a water craft. These are (i) the hydrofoilapproach, which generally provides high speed; and (ii) the SWATHapproach, which generally provides high stability.

The Hydrofoil Approach

Hydrofoils have been in experimental use for many years, and today arein active service around the world for a variety of applications.Hydrofoils generally employ small airplane-like wings (“lifting foils”)which provide lift for the hull of the vessel. These lifting foils aretypically lowered into the water while the vessel is underway. At higherspeeds, the lifting foils are capable of lifting the hull of the vesselcompletely out of the water, thereby allowing the vessel to operate withonly its lifting foils (and their supporting struts) in the water,whereby to minimize drag and increase vessel speed. However, the liftingfoils themselves provide no buoyancy and therefore cannot support thevessel at slower speeds. Thus, the vessel can only operate in hydrofoilmode when moving at substantial speeds. In addition, due to the thinnature of the hyrdofoil's lifting foils, it is not possible to house thevessel's engines within the lifting foils themselves—instead, it isnecessary to house the engines within the hull of the vessel and to usetransmission technologies (e.g., mechanical, hydraulic and/or electricalmeans) to transfer power from the vessel's engines down to its liftingfoils, which carry the propellers. However, these power transmissiontechnologies all involve substantial losses in power (therebynecessitating the use of larger engines and/or resulting in lowerspeeds) and significantly complicate the propulsion system of thevessel.

The SWATH Approach

SWATH vessels employ two or more torpedo-shaped structures which aredisposed underwater and attached to the main body of the vessel withfixed vertical struts. The torpedo-shaped structures provide buoyancyfor the main body of the vessel, which remains completely out of thewater. In this way, SWATH vessels resemble catamarans, except that thetwo pontoon hulls of the catamaran are replaced by underwatertorpedo-shaped structures which reside immediately below the hull at theends of the vertical struts. The SWATH design generally providesexcellent stability because the underwater torpedo-shaped structures areless affected by wave action than a traditional wave-riding hull.However, the substantial skin friction, and the inefficient hydromanticshape, of the large underwater torpedo-shaped structures generallyresults in higher power consumption. This higher power consumption inturn necessitates the use of larger engines and/or results in reducedvessel speed. However, the use of larger engines is itself problematic,since the engines must then be housed in the hull or, if the engines areto be housed in the underwater torpedo-shaped structures, the underwatertorpedo-shaped structures must be enlarged. Housing the engines in thehull introduces all of the power transmission problems discussed abovewith respect to hydrofoils, since the propellers are mounted to theunderwater torpedo-shaped structures. Conversely, enlarging theunderwater torpedo-shaped structures increases the skin frictionproblems, and the inefficient hydromantic shape problems, discussedabove—which in turn necessitates the use of even larger engines. Forthis reason, it has previously been impossible to build a small,high-speed SWATH vessel. In addition to the foregoing, the SWATH designtypically requires a high profile in order to ensure that the hull ofthe vessel remains completely out of water, particularly in high seas.This gives the SWATH vessel larger radar, infrared and visualsignatures, thereby making it easy to detect and target.

Novel Approach for Achieving High Speed and Extreme Stability

The present invention overcomes the problems associated with the priorart through the provision and use of novel fleet protection attack craft5. Attack craft 5 supports its command module 100 on a pair of buoyanttubular foils (BTFs) 200 via movable struts 300. BTFs 200 normallyprovide all of the buoyancy required for the craft, with command module100 remaining completely out of the water. More particularly, BTFs 200and struts 300 are normally the only portions of the craft which contactthe water, and they provide low friction hydromantic cross-sections soas to minimize water resistance. Significantly, BTFs 200 housesubstantially all of the propulsion, fuel and steering systems for thecraft, thereby providing the craft with an unusually low center ofgravity and permitting the volume of command module 100 to be dedicatedto crew, weapons and payload. Furthermore, struts 300 are movablerelative to command module 100, thereby permitting the craft to assume anumber of different configurations. This unique approach results in acraft with unparalleled speed and stability regardless of seaconditions, and with lower radar, infrared and visual signatures,thereby making it difficult to detect and target. Various aspects of thecraft will now be discussed in further detail.

Command Module 100

Looking now at FIGS. 1-9, command module 100 generally comprises awatertight enclosure 105 (FIG. 3) having a hull-like bottom surface 110(FIGS. 4, 5, 7 and 8). Command module 100 includes a cockpit 115 (FIGS.2, 3, 6 and 8) for housing a pilot and weapons officer, and a bay 120(FIG. 9) for housing weapons and payload (including passengers). Commandmodule 100 includes a rear hatch 125 (FIGS. 5, 6 and 9) for permittingentry and exit of crew, weapons and payload (including passengers), anda top hatch 130 (FIGS. 2, 6 and 9) for permitting various weaponssystems to be raised out of bay 120, fired, and then lowered back intobay 120.

Command module 100 is armored to protect all occupants, weaponry andpayload. Windscreens 135 (FIGS. 7 and 9) are formed out ofbullet-resistant materials.

Command module 100 comprises watertight bulkhead enclosures which,combined with hull-like bottom surface 110, allow waves to wash over thecommand module without effect when attack craft 5 is operating in itsstealth mode (see below). Automatic vent doors seal any open systemsagainst water leakage when attack craft 5 is in this stealth mode.

The outer structure of command module 100 is preferably based onso-called “stealth” principals in order to minimize the radar signatureof the craft. More particularly, the outer surface of command module 100is designed to deflect radar energy and return only a minimal amount ofradar energy to the radar transmitter. To this end, the exteriorsurfaces of command module 100 are preferably highly angular, with theangles being selected so as to reflect the radar energy either downwardtowards the water or upward into the sky. In any case the exteriorsurfaces of command module 100 minimize the amount of radar energyreflected directly back to the sender. Furthermore, command module 100preferably incorporates a radar-absorbent paint which is capable ofabsorbing or further reducing any incident radar energy.

Command module 100 is also configured to house all of the controlsystems for piloting the attack craft, all of the weapons controlsystems for operating the weapons carried by the attack craft, anauxiliary generator for supplemental power requirements (e.g., fornavigation), a battery charger, an air filtration system, a head, asink, an air compressor, etc.

The weapons systems carried by attack craft 5 preferably comprise (i)one 20 mm Vulcan Gatling gun, equipped with optic and night vision; (ii)two 30 caliber Miniguns equipped with optic and night vision; (iii) oneor more 2.5 inch laser-guided rockets; and (iv) 8 “mini” torpedoes.Preferably the Gatling gun, Miniguns and rockets are housed within bay120 for elevated deployment through top hatch 130, and the “mini”torpedoes are mounted to the exterior of command module 100, e.g., suchas is shown at 140.

Buoyant Tubular Foils (BTFs) 200

Looking next at FIGS. 10-15, a pair of buoyant tubular foils (BTFs) 200provide buoyancy, propulsion and steering for attack craft 5. Each ofthe BTFs 200 generally comprises a hollow tubular structure 205 whichhouses an engine 210 for powering a propeller system 215, a fuel tank220 for supplying fuel to engine 210, and steering elements (orspoilers) 225 for steering attack craft 5.

Hollow Tubular Structure 205

Hollow tubular structure 205 generally comprises a hollow hull whichprovides buoyancy for attack craft 5. Hollow tubular structure 205 isconfigured so as to provide stability at low speed operations whilestill providing low water friction and an improved hydromantic profileso as to enable speeds of over 80 knots. At high speeds, theconfiguration of hollow tubular structure 205 provides extraordinarystability for the vessel, due to the flow of water over the elongatedtubular structure.

More particularly, the low friction hydromantic cross-section of hollowtubular structure 205 traverses water with the lowest possible skinfriction forces and the best hydromantic shape obtainable, yet stillhouses engine 210 and fuel tank 220, and supports propeller system 215and steering elements 225. It has been determined that best performanceis achieved where hollow tubular structure 205 has a cross-section whichis between about 1/10 and about 1/30 of the length of hollow tubularstructure 205, and preferably about 1/20 of the length of the hollowtubular structure. By way of example but not limitation, excellentperformance can be achieved where hollow tubular structure 205 has a 3foot outer diameter and a 60 foot length.

As seen in FIGS. 12-15, hollow tubular structure 205 comprises aplurality of disconnectable sections that permit easy access tocomponents disposed within the interior of hollow tubular structure 205,e.g., for maintenance and quick replacement of power and sensor modules.By way of example but not limitation, hollow tubular structure 205 cancomprise a center section 230 which is mounted to a strut 300, a forwardsection 235 which is dismountable from center section 230, and a rearsection 240 which is dismountable from center section 230. Preferably,interior components may be equipped with slides for easy entry into, andremoval from, hollow tubular structure 205. By way of example but notlimitation, FIG. 14 shows how engine 210 may be equipped with slides 245for supporting engine 210 within hollow tubular section 205, and tofacilitate insertion into, and removal from, hollow tubular structure205.

Front section 235 and rear section 240 can mount to center section 230in a variety of ways. By way of example but not limitation, the sectionscan be mechanically held together (e.g., by hydraulics, power screwactions, etc.) or they can twist lock together (e.g., in the manner of abayonet-type mount). A watertight seal is provided between the sectionsso as to ensure hull integrity. The seal can be a continuous circularshape to match the cross-section of hollow tubular structure 205, e.g.,a resilient O-ring having a round or flat cross-section. Alternatively,the O-ring can be an inflatable seal (e.g., like the inner tube of abicycle tire) that can provide adjustable sealing forces by theinjection of an appropriate amount of fluid (e.g., gas or liquid).Preferably, each O-ring seal has two sealing surfaces, i.e., the facesurface between adjacent sections and the face surface against the skinof hollow tubular structure 205.

The ability to quickly unlock the various sections of hollow tubularstructure 205 permits the rapid servicing and/or replacement of thevarious components contained within hollow tubular structure 205, e.g.,engine 210, fuel tank 220, etc.

Gas Turbine (Jet) Engine Propulsion

Engine 210 can be a conventional diesel engine, internal combustionengine, rotary engine, electric motor, etc. Preferably, however, engine210 comprises a gas turbine (jet) engine, e.g., of the sort used inaircraft, and particularly of the sort used in helicopters. A gasturbine engine is preferred due to its high power, small size and lowweight. More particularly, a gas turbine engine typically has ahorsepower-to-weight ratio of about 2.5 horsepower (HP) per pound. Bycomparison, a modern marine diesel engine typically has ahorsepower-to-weight ratio of about 0.5 HP per pound. Since there isgenerally a direct correlation between vessel acceleration and weight,it is generally desirable to use a high power, low weight engine whendesigning a high speed craft. Thus, a gas turbine engine is thepreferred propulsion unit for attack craft 5.

Significantly, a gas turbine engine is also ideal for use in attackcraft 5 since its size and configuration is perfectly suited fordisposition within hollow tubular structure 205. More particularly, gasturbine engines typically have an elongated, somewhat cylindricalconfiguration which easily fits within a hollow tubular structure.Significantly, gas turbine engines generally have relatively modestcross-sections, such that the gas turbine engines can fit within arelatively small diameter tube. By way of example but not limitation,the T53L13 gas turbine (jet) engine manufactured by Lycoming Engines (adivision of Avco Corporation, a wholly owned subsidiary of Textron,Inc.) of Williamsport, Pa. has a diameter which is ideally suited fordisposition within hollow tubular structure 205 of attack craft 5.

The use of a gas turbine engine in BTFs 200 also provides significantadditional advantages.

First, the use of a gas turbine engine in each BTF 200 easily allows forthe use of a centerline drive shaft to transfer power to propellersystem 215. This is an enormous advantage when it comes to efficientlydelivering large amounts of power to propeller system 215.

Second, the gas turbine engine provides a starter generator thatperforms two functions, i.e., (i) to start the turbine engine, and (ii)to generate DC power. More particularly, most gas turbine enginesprovide 24 volts DC at 300 amps. This allows attack craft 5 to power allof its electrical systems from the gas turbine engines, with the needfor only a small supplemental generator for charging batteries.

In addition, placing a gas turbine engine inside hollow tubularstructure 205, which is always underwater, also provides superiorcooling for the gas turbine engine since the radiated engine heat istransferred to the surrounding water through the skin of hollow tubularstructure 205.

Furthermore, gas turbine engines are generally designed to be quicklyand easily removed (e.g., by sliding) from an aircraft fuselage.Similarly, the gas turbine engine can be quickly and easily removed(e.g., by sliding) from hollow tubular structure 205.

The gas turbine engine usually has a high internal rpm (greater than19,000 rpm) with internal gear reductions. Preferably, a gearbox 250using planetary gears connects engine 210 to propeller system 215. Thisapproach provides a gearbox which is smaller than the outside diameterof the gas turbine engine.

Gas Turbine (Jet) Engine Intake and Exhaust

The “Achilles heel” of a gas turbine engine is its need to rapidlyintake large quantities of fresh air and to rapidly expel largequantities of exhaust air. As a result of this need to rapidly movelarge quantities of air in and out of the gas turbine engine, gasturbine engines have not heretofore been a candidate for use inunderwater structures (e.g., submarines and the submerged portions ofSWATH vessels) due to the inability to adequately aspirate the jetengines.

A critical aspect of attack craft 5 is the air intake and exhaustsystems which support the use of gas turbine engines underwater. In thisrespect it will be appreciated that the design of the air intake andexhaust systems is complicated by the fact that attack craft 5 isdesigned to change configurations (e.g., as shown in FIGS. 4, 7 and 8)and the air intake and exhaust systems must be able to accommodate theseconfiguration changes. More particularly, with attack craft 5, the gasturbine engines are housed underwater in BTFs 200, the BTFs 200 aredisposed at the ends of struts 300, and struts 300 are movable relativeto command module 100 (see FIGS. 4, 7 and 8). Thus, the air intake andexhaust systems of attack craft 5 must be capable of rapidly movinglarge quantities of air in and out of the gas turbine engines, andthrough struts 300, while at the same time accommodating movement ofstruts 300 relative to command module 100.

To this end, attack craft 5 comprises an air intake and exhaust systemfor rapidly delivering large quantities of fresh air to gas turbineengine 210 and for rapidly expelling large quantities of exhaust airfrom gas turbine engine 210. The air intake and exhaust system generallycomprises an engine intake duct 255 and an engine exhaust duct 260. Theintake side of engine intake duct 255 is disposed in command module 100so that it can access cool air, which increases the efficiency of gasturbine engines 210. Preferably, the intake side of engine intake duct255 is funneled so as to generate ram air forces while attack craft 5 ismoving at speed, which further increase the efficiency of gas turbineengines 210. The outlet side of engine exhaust duct 260 is disposed incommand module 100 so as to provide efficient exhaust venting with aminimal heat signature. Engine intake duct 255 and engine exhaust duct260 preferably pass through a flexible coupling located at the junctionof the strut and the command module, in order to accommodate movement ofthe strut vis-à-vis the command module. This flexible coupling alsoaccommodates other lines passing from command module 100 to BTFs 200 viastruts 300, e.g., fuel re-fill lines, electrical power lines, electricalcontrol lines, etc.

It should be appreciated that the flexible coupling is configured so asto allow engine intake and engine exhaust to be vectored and bent whilestill accommodating the large gas volumes associated with the gasturbine engine. Furthermore, the flexible coupling is designed toaccommodate the high exhaust temperatures created by the gas turbineengine. The use of heat-resistant flexible materials in the coupling isessential to allow movement of the struts relative to the commandmodule.

It should also be appreciated that moving large quantities of airthrough a narrow strut (which is thinner than BTF 200) entails usingsubstantially the entire inner structure of the strut as an air intakeduct and an engine exhaust duct. In one preferred form of the invention,engine exhaust duct 260 is routed inside air intake duct 255 so as toallow the exhaust to be cooled by the intake air, whereby to provide alower thermal, signature for attack craft 5. In another preferred formof the invention, engine exhaust duct 260 is not routed inside airintake duct 255—rather, in this form of the invention, engine exhaustduct 260 is separate from air intake duct 255, and the exhaust in engineexhaust duct 260 is separately cooled, e.g., with a water coolingjacket. Furthermore, in this form of the invention, insulation may beused to keep the cool air in air intake duct 255 from being heated bythe hot exhaust in engine exhaust duct 260 in order to increase theefficiency of gas turbine engines 210.

Preferably, engine exhaust duct 260 includes insulation to prevent theheat of gas turbine engine 210 from overheating the outer skin of strut300.

In one form of the present invention, engine exhaust ducts 260 aredouble-walled, so as to allow a fluid to be circulated around the innerhot duct, whereby to further cool the engine exhaust and provide a lowerthermal signature.

Attack Craft Propulsion Using Battery Power

Preferably, attack craft 5 also includes an electric motor (not shown)and batteries (not shown) for selectively driving propeller system 215.More particularly, in certain circumstances (e.g., reconnaissanceoperations and the delivery and/or extraction of special forces) it maybe desirable to operate with reduced noise. In these circumstances, theelectric motor and batteries may be used in place of the gas turbine(jet) engine discussed above.

Propeller System 215

Most vessels in use today utilize propellers which are disposed at thestern of the vessel and push the vessel through the water. This approachis generally satisfactory for most vessels. However, stern-mounted,pushing propellers are generally not satisfactory for those vesselswhich are trying to achieve very high speeds, e.g., speeds in excess of80 knots. This is because propellers located at the stern of the vesselengage water which has been agitated by the prior passage of the vesselthrough the water. Since the efficiency of propellers is highly affectedby the state of the water the propellers move through, stern-mounted,pushing propellers are generally impractical for high speed craft.

Some high speed boats in use today (e.g., hydroplanes and ocean racingboats) use stern-mounted, surface-penetrating, forward-facing propellersthat ride partially submerged in agitated water with air mixed in. Thesepiercing propellers are designed with a heavy trailing edge andanti-cavitation cupping. These piercing propellers withstand the extremeforces of high horsepower and high rpm because the propeller is neverfully engaged in the water.

However, this type of propeller would not be effective for attack craft5, since with BTF 200, propeller system 215 must be fully submerged.

Significantly, the present invention utilizes a propeller system 215which comprises a pair of forward-facing, pulling, counter-rotatingpropellers 265, 270 located at the bow end of each BTF 200.

More particularly, a propeller system 215 is placed at the bow of eachBTF 200 so that the forward-facing, pulling propellers can “bite” intovirgin water, whereby to obtain maximum efficiency. Furthermore, eachpropeller system 215 comprises two propellers, a leading propeller 265and a trailing propeller 270, operated in a timed, counter-rotatingmode, so as to provide reduced cavitation for the forward propeller.Leading propeller 265 is the main propulsion element and does themajority of the work of pulling of the vessel. Trailing propeller 270spins in the opposite direction from the leading propeller and evacuateswater from behind the leading propeller, thereby permitting the leadingpropeller to work with maximum efficiency. In other words, trailingpropeller 270 moves water out from behind leading propeller 265 so thatthe leading propeller can pull more water in. This provides increasedpropeller efficiency, which translates into higher speed and lower fuelconsumption.

Using serially-mounted, counter-rotating propellers 265, 270 alsopermits smaller propeller diameters to be used. This is because thesurface areas of the two propellers combine so as to provide an overalleffective surface area which is equivalent to the surface area of asingle, larger diameter propeller. However, it is difficult to rotate alarge diameter propeller at high speeds due to the forces involved.Thus, the use of serially-mounted, counter-rotating propellers permitsthe propellers to be rotated at higher rpms, thereby permitting higherspeeds to be achieved.

In addition to the foregoing, by using two counter-rotating propellers,there is no side torque. More particularly, side torque in propellers isthe result of the centrifugal forces created by the rotation of thepropeller. This side torque creates a tendency for the vessel to turn inthe direction of the rotation of the blade. Side torque is not desiredwith attack craft 5, since it involves a loss of energy and can createsteering issues for the vessel.

A gearbox 250 connects a gas turbine engine 210 to a propeller system215. More particularly, gearbox 250 is configured to convert the singlerotational motion of the output shaft of a gas turbine engine 250 intothe dual, co-axial, counter-rotational motions needed to drive thecounter-rotating propellers, 265, 270.

Super-Cavitation

By placing the counter-rotating propellers 265, 270 on the forward endof BTFs 200, the propellers are able to pull the vessel through clean,undisturbed, virgin water, thereby ensuring optimal propellerperformance. In addition, by placing the two serially-mounted,counter-rotating propellers on the fount end of BTFs 200, attack craft 5is able to generate a highly gaseous environment, comprising a jetstream of dense collapsing bubbles, that encapsulates BTFs 200 andsignificantly reduce vessel drag. More particularly, the actions ofpropellers 265, 270, working together, pull water through the leadingpropeller 265 and allowing the trailing propeller 270 to heavilycavitate the rapidly moving water and create a heavy stream of gaseousbubbles which surround the outer surfaces of BTFs 200. This gaseousenvelope reduces hull drag and greatly increases the speed of thevessel, since the BTFs are essentially “flying through bubbles”. SeeFIG. 15A. In this respect it should be appreciated that the kineticcoefficient of friction with air is approximately 1/800th the kineticcoefficient of friction of water. Furthermore, the faster the vesselgoes, the greater the reduction in hull friction, inasmuch as (i) thegreater the quantity of gaseous bubbles which are created by theserially-mounted, counter-rotating propellers, and (ii) the bubbles donot have time to collapse before BTFs 200 have passed completely throughthem.

Attack craft 5 can also include additional means for producing anencompassing gaseous envelope. More particularly, a plurality of smallholes 275 (FIG. 15B) are preferably located just behind trailingpropeller 270 and disposed in a circler fashion about the periphery ofthe BTF structure. These holes 275 are in communication with ductworkleading to the outside air, allowing the trailing propeller to create asiphon effect, drawing air down for release just aft of the trailingpropeller, whereby to create an even more dense gaseous envelope forreducing BTF friction. Alternatively, a pressurized gas source connectedto small holes 275 can also be used to release gas just aft of thetrailing propeller, whereby to create the desired gaseous envelope forreducing BTF friction. In yet another form of the invention, a supply offriction-reducing fluid (e.g., detergent) can be connected to theaforementioned small holes 275, whereby to create the desiredfriction-reducing envelope about BTFs 200.

Rudderless System

Conventional rudders are continuously deployed in the water, so thatthey create friction and drag not only when being manipulated so as tochange the direction of the vessel, but also under normal operatingconditions. This friction and drag has a substantial detrimental effecton the speed of the vessel.

In contrast, and looking now at FIGS. 16-26, attack craft 5 providesforward and aft steering elements (or spoilers) 225 that are projectablefrom, and retractable into, the outer skin of hollow tubular structure205. In this respect it should be appreciated that each of the spoilers225 can be projected an adjustable amount outboard from hollow tubularstructure 205. Furthermore, command module 100 can be provided withvarious control systems which permit each of the spoilers 225 to beoperated in a coordinated fashion or, if desired, independently from oneanother.

In one preferred form of the invention, sixteen spoilers 225 areprovided: four spoilers 225 at the front of each BTF 200 and fourspoilers 225 at the rear of each BTF 200, with spoilers 225 beingdisposed at the “12 o'clock”, “3 o'clock”, “6 o'clock”, and “9 o'clock”positions. This arrangement allows spoilers 225 to apply left, right, upand/or down forces (or any combination thereof) to the front and/or rearof each of the BTFs 200 while attack craft 5 is underway.

Spoilers 225 provide numerous significant advantages over conventionalrudders.

For one thing, spoilers 225 provide substantially no drag when thevessel is underway and no directional changes are needed—this is becausethe spoilers then reside flush with the outer skins of hollow tubularstructures 205. Spoilers 225 impose drag on the vessel only when theyare extended outwardly from the skins of hollow tubular structures 205,whereby to provide the forces necessary to maneuver the vessel—and theyare thereafter returned to their inboard (i.e., flush, and no-drag)positions as soon as the maneuver is completed and the vessel returns tostandard forward motion.

Additionally, and significantly, the provision of spoilers 225 on thefore and aft portions of hollow tubular structures 205 permits theapplication of more dramatic turning forces. More particularly, bysetting a fore spoiler to turn in one direction and a corresponding aftspoiler to turn in the opposite direction, significant turning forcescan be quickly and easily applied to the vessel using spoilers ofrelatively modest size. Thus, course corrections can be effectedquickly, making the vessel extremely agile, while permitting the turningfriction of the spoilers to be applied only for short durations.

Spoilers 225 can be used for turning left or right (see FIGS. 16-19),for adjusting the trim (i.e., the up/down attitude) of the vessel (seeFIGS. 20-23), and/or to enhance deceleration of the vessel (see FIGS.24-26).

Spoilers 225 can be flush plates that protrude from the outer skins ofhollow tubular structures 205 and cause friction when needed to changedirection. Alternatively, spoilers 225 can be made of an elastomericmaterial that can be inflated with air, fluids, etc. and which protrudefrom the outer skins of hollow tubular structures 205.

Fuel Tanks 220

Fuel tanks 220 are housed inside BTFs 200, preferably in the centersection 230. Fuel tanks 220 preferably comprise double-walled tanks madeof a flexible bladder material (e.g., a flexible bladder disposed insideanother flexible bladder). This arrangement allows for a fluid (e.g.,seawater) to be pumped into the outer bladder in order to compensate forthe consumption of fuel from within the inside bladder, thereby ensuringthat the buoyancy of the attack craft remains constant.

Center Of Gravity

The center of gravity for attack craft 5 is intended to be as low aspossible, in order to maximize vessel stability. This is achieved bypositioning heavy components such as engines 210 and fuel tanks 220within the BTFs, thereby lowering the vessel's center of gravity so asto be as close as possible to the midline of the BTFs. In this respectit will be appreciated that turbine engines 210 and fuel tanks 220constitute approximately ⅔ of the total vessel weight and, due to theconstruction of attack craft 5, this weight is disposed entirely belowthe waterline. This leads to enhanced vessel stability.

Connecting Struts 300

As noted above, connecting struts 300 attach BTFs 200 to command module100. As also noted above, struts 300 are designed to be fixed to BTFs200 and pivot on command module 100 so as to allow attack craft 5 toassume different configurations (FIGS. 4, 7 and 8), whereby to permitcommand module 100 to sit different distances from the water. As seen inFIGS. 27-36, struts 300 comprise hydraulic or electric jack screws 305connected to load arms located within struts 300, whereby to move struts300 relative to command module 100. In this respect it will beappreciated that FIGS. 27-29 show struts 300 in a position correspondingto the attack craft configuration shown in FIG. 4, FIGS. 30-32 showstruts 300 in a position corresponding to the attack craft configurationshown in FIG. 7, and FIGS. 33-36 show struts 300 in a positioncorresponding to the attack craft configuration shown in FIG. 8.

Since struts 300 extend into the water, it is important to keep thestruts as thin as possible so as to minimize drag.

It should also be appreciated that the structural integrity of struts300 relies primarily on the strength of the load arms located within thestruts acting in conjunction with the outer skin of the struts, whileusing minimal internal frames. This is important, since struts 300 needto have large areas of uninterrupted volume in order to permit engineintake to pass uninterrupted through the interior of the struts.

Fly-by-Wire Controls

In one preferred form of the invention, sensors are located on hull-likebottom surface 110 of command module 100 and continuously measure thedistance of the command module from the water surface. A computerautomatically adjusts the disposition of struts 300 so as to maintainthe command module a desired distance above the water surface. In thisrespect it will be appreciated that, particularly when attack craft 5 isoperating at high speeds (e.g., 80 knots) in open water, it is importantto keep command module 100 from coming into contact with the surface ofthe water (and particularly important to keep command module 100 fromcoming into contact with the irregular sea swells commonly found in theopen sea).

Thus, for example, in standard seas, attack craft 5 might be placed inthe configuration shown in FIG. 4 so that command module 100 is safelyout of the water and the vessel has modest radar, infrared and visualsignatures.

However, in high seas, while operating at high speed, attack craft 5might be placed in the configuration shown in FIG. 7 so that commandmodule 100 stands well out of the water and is free from the affect ofswells.

Furthermore, depending on sea conditions, attack craft 5 could be in aconfiguration somewhere between those shown in FIGS. 4 and 7.

Attack craft 5 is also designed to operate in stealth mode, by loweringits physical profile. In this case, attack craft 5 might be placed inthe configuration shown in FIG. 8 so that command module 100 sits justabove, or actually in, the water, reducing its radar, infrared andvisual signatures. This mode can be very useful when attack craft 5 isbeing used for reconnaissance purposes and/or to deliver small teams ofspecial forces behind enemy lines and/or to extract the same.

Thus, in one preferred form of the invention, attack craft 5 is normallyoperated in the configuration shown in FIG. 4, with command module 100completely out of the water; but the command module being as low aspossible so as to have a reduced profile. However, in high seas and athigh speed, attack craft 5 may be operated on the configuration shown inFIG. 7, so that command module 100 stands well clear of any swells. And,when desired, attack craft 5 can be operated in the configuration shownin FIG. 8 so as to assume a stealth mode.

Or, attack craft 5 could be operated in a configuration somewherebetween those shown in FIGS. 4, 7 and 8.

Preferably, speed sensors feed speed data to a main computer, whichadjusts the sensitivity of the steering controls so that, whiletravelling at low speeds, the controls are more reactive and whentravelling at high speeds, the controls are less reactive. In otherwords, the main computer preferably adjusts the sensitivity of thesteering controls so that (i) large movements of the steering controls(e.g., a joystick) are required at high speeds to make modest changes inthe disposition of spoilers 225, and (ii) small movements of thesteering controls are required at slow speeds to make significantchanges in the disposition of spoilers 225. This construction eliminatesthe possibility that a modest movement of the controls at high speedwill result in a catastrophic change in the direction or attitude of thecraft.

Extendable BTF Boom

If desired, BTFs 200 can be provided with an extendible boom. This boomis deployable from the rear end of the BTF, and is preferably flexible.The extendible boom can serve two purposes.

First, the extendible boom can have controllable surface protrusionsalong its length that can be enlarged or contracted so as to allow dragto be applied to the boom, thus further stabilizing the BTF in a mannersimilar to the tail of a kite. The protrusions cause drag thatstabilizes the vessel in both the horizontal and vertical planes. Theprotrusions can be controlled by elastic bladders which are inflated soas to increase size (and hence drag) as desired, or a mechanical devicelocated at the end of the boom that provides mechanical drag resistance,thereby increasing stability.

Second, the extendible boom can also house sonar, listening devices,magnetometers, gravity interruption sensors, etc. that can be used forthe identification of submerged objects. By mounting these devices onthe end of an extendible boom, the devices can be isolated from theremainder of attack craft 5, so as to minimize interference with devicefunction.

Non-Military and Civilian Applications

In the foregoing description, attack craft 5 is described in the contextof its use for military applications. However, it should be appreciatedthat attack craft 5 may also be used for other, non-militaryapplications such as security applications (e.g., police, immigrationand drug enforcement purposes), public safety applications (e.g., searescues), high-speed servicing and re-supply applications (e.g., forservicing oil drilling platforms), high-speed water taxi applications,private pleasure craft applications, etc.

Modifications of the Preferred Embodiments

It should be understood that many additional changes in the details,materials, steps and arrangements of parts, which have been hereindescribed and illustrated in order to explain the nature of the presentinvention, may be made by those skilled in the art while still remainingwithin the principles and scope of the invention.

What is claimed is:
 1. A marine vessel comprising: a command module;first and second buoyant tubular foils; and first and second struts forconnecting the first and second buoyant tubular foils to the commandmodule, respectively, the first and second buoyant tubular foils eachcomprising a cylindrical structure defined by a skin having an innerdiameter and an outer diameter; wherein the first and second buoyanttubular foils provide substantially all of the buoyancy required for themarine vessel; wherein the marine vessel further comprises first andsecond engines enclosed within the first and second buoyant tubularfoils, respectively, and first and second propulsion units connected tothe first and second engines, respectively, for moving the marine vesselthrough the water; and wherein the first and second engines eachcomprise aircraft gas turbine jet engines and are each characterized byhigh power, small size, low weight and an elongated cylindricalconfiguration for sliding disposition within the interior of thecylindrical structure and which closely match the inner diameter of thecylindrical structure of the buoyant tubular foil such that heatradiated from the gas turbine jet engine is transferred to watersurrounding the buoyant tubular foil through the skin of the cylindricalstructure.
 2. A marine vessel according to claim 1 wherein the first andsecond struts are pivotally connected to the command module and fixedlyconnected to the first and second buoyant tubular foils, respectively;and wherein the first and second struts comprise substantially rigidplanar structures.
 3. A marine vessel according to claim 2 wherein themarine vessel is reconfigurable between (i) a “standard” configurationwherein the first and second struts are disposed approximately 45degrees off the horizon; (ii) a “high seas” configuration wherein thefirst and second struts are disposed substantially perpendicular to thehorizon; and (iii) a “stealth” configuration wherein the first andsecond struts are disposed so that the bottom of the command module isadjacent to or in the water.
 4. A marine vessel according to claim 2wherein the marine vessel is continuously reconfigurable between (i) afirst configuration wherein the first and second struts approach aco-linear disposition, and (ii) a second configuration wherein the firstand second struts are disposed substantially perpendicular to thehorizon.
 5. A marine vessel according to claim 2 wherein the marinevessel further comprises a control system for (i) determining the heightof the command module above the surface of the water; and (ii) adjustingthe disposition of the first and second struts relative to the commandmodule so as to maintain the command module a substantially fixed heightabove the water.
 6. A marine vessel according to claim 1 wherein each ofthe buoyant tubular foils has a length:width ratio of between 10:1 and30:1.
 7. A marine vessel according to claim 1 wherein each of thebuoyant tubular foils has a length:width ration of approximately 20:1.8. A marine vessel according to claim 1 wherein the gas turbine jetengines are aspirated via the first and second struts, respectively. 9.A marine vessel according to claim 8 wherein each of the gas turbine jetengines are aspirated by an intake duct and an exhaust duct, and furtherwherein the intake duct and the exhaust duct comprise couplings at thelocations where the intake duct and the exhaust duct extend between astrut and the command module.
 10. A marine vessel according to claim 9wherein the couplings are flexible.
 11. A marine vessel according toclaim 9 wherein at least a portion of the exhaust duct is disposedinterior the intake duct.
 12. A marine vessel according to claim 1further comprising first and second fuel tanks for storing the fuel forthe first and second engines, respectively, and further wherein thefirst and second fuel tanks are enclosed within the first and secondbuoyant tubular foils, respectively.
 13. A marine vessel according toclaim 12 wherein the first and second fuel tanks are configured tocompensate for the consumption of fuel from the first and second fueltanks so as to maintain constant buoyancy for the marine vessel.
 14. Amarine vessel according to claim 13 wherein the first and second fueltanks each comprise an inner bladder and an outer bladder, and furtherwherein the inner bladder contains the fuel and the outer bladdercontains a weight-compensating fluid.
 15. A marine vessel according toclaim 14 wherein the contents of the outer bladder are increased as thecontents of the inner bladder are decreased.
 16. A marine vesselaccording to claim 14 wherein the weight-compensating fluid comprisessea water.
 17. A marine vessel according to claim 1 wherein the firstand second propulsion units comprise first and second propellermechanisms mounted on the leading ends of the first and second buoyanttubular foils, respectively, for moving the marine vessel through thewater.
 18. A marine vessel according to claim 17 wherein the first andsecond propeller mechanisms each comprise a leading propeller and atrailing propeller, and further wherein the leading propeller and thetrailing propeller rotate in opposing directions.
 19. A marine vesselaccording to claim 18 wherein the first and second engines drive thefirst and second propeller mechanisms, respectively, and further whereinthe first and second engines are disposed in line with the first andsecond propeller mechanisms, respectively.
 20. A marine vessel accordingto claim 19 wherein the first and second engines are connected to thefirst and second propeller mechanisms, respectively, via first andsecond gearboxes, respectively, and further wherein each gearbox isconfigured to convert the single rotational motion of an output shaft ofan engine into the dual, co-axial, counter-rotational motion needed todrive the leading and trailing propellers of a propeller mechanism. 21.A marine vessel according to claim 17 wherein the marine vessel furthercomprises first and second supercavitation units for generating a streamof gas bubbles, wherein the first and second supercavitation units aredisposed on the first and second buoyant tubular foils just aft of thefirst and second propeller mechanisms, respectively, so that the firstand second supercavitation units encapsulate the first and secondbuoyant tubular foils, respectively, with a stream of gas bubbles so asto reduce the drag thereof.
 22. A marine vessel according to claim 17further comprising a supply of friction-reducing fluid, the supply offriction-reducing fluid being deployable just aft of the first andsecond propeller mechanisms, respectively, so as to encapsulate thefirst and second buoyant tubular foils with the friction-reducing fluidso as to reduce the drag thereof.
 23. A method for moving through water,the method comprising: providing a marine vessel comprising: a commandmodule; first and second buoyant tubular foils; and first and secondstruts for connecting the first and second buoyant tubular foils to thecommand module, respectively, the first and second buoyant tubular foilseach comprising a cylindrical structure defined by a skin having aninner diameter and an outer diameter; wherein the first and secondbuoyant tubular foils provide substantially all of the buoyancy requiredfor the marine vessel; wherein the marine vessel further comprises firstand second engines enclosed within the first and second buoyant tubularfoils, respectively, and first and second propulsion units connected tothe first and second engines, respectively, for moving the marine vesselthrough the water; and wherein the first and second engines eachcomprise aircraft gas turbine jet engines and are each characterized byhigh power, small size, low weight and an elongated cylindricalconfiguration for sliding disposition within the interior of thecylindrical structure and which closely match the inner diameter of thecylindrical structure of the buoyant tubular foil such that heatradiated from the gas turbine jet engine is transferred to watersurrounding the buoyant tubular foil through the skin of the cylindricalstructure; and moving the marine vessel through water.
 24. A methodaccording to claim 23 wherein the first and second struts are pivotallyconnected to the command module and fixedly connected to the first andsecond buoyant tubular foils, respectively; and wherein the first andsecond struts comprise substantially rigid planar structures; andadjusting the position of the first and second struts relative to thecommand module.
 25. A method according to claim 23 wherein the first andsecond propulsion units comprise first and second propeller mechanismsmounted on the leading ends of the first and second buoyant tubularfoils, respectively, for moving the marine vessel through the water. 26.A marine vessel according to claim 1 further comprising slides forsupporting the first and second engines within the first and secondbuoyant tubular foils, respectively, and for facilitating insertioninto, and removal from, the first and second buoyant tubular foils. 27.A marine vessel according to claim 1 wherein each of the buoyant tubularfoil comprises a 3 foot outer diameter and a 60 foot length.